Cancer is the second overall leading cause of death, after ischemic heart disease, in the United States and Western Europe and despite recent advances in its treatment, there is, for most cancer types, no miracle cure on the horizon. Cancer causes approximately 25% of all deaths. The incidence continues to rise, probably reflecting the increasing average age of the population. The key to survival is early diagnosis and treatment.
About two decades ago HPV was associated with human tumors. Since then it has been detected in tumors and (pre)neoplastic lesions of different sites such as uterine cervix, penis, skin, middle ear, anus, squamous cell tumours of the head and neck region (oral mucosa, tonsil, larynx, pharynx), lung, urinary bladder.
More than 70 different types of HPV have been reported with different relations to the progression of a lesion. Some of the types have stronger association with the progression to malignant tumors than others e.g. type 16 and 18 are associated with high grade intraepithelial dysplasia of the cervix. These are called ‘high risk’ HPV types. The number of HR-HPV has been expanded the last years to e.g. 16, 18 45, 31, 33 . Other types are mainly associated with benign tumors such type such as 1,2, 4, 5, and 6 with benign skin warts. HPV type 11 is frequently present in juvenile recurrent respiratory papillomas. Frequently in a series of cases of one histologic type of lesion different HPV types have been detected. Occasionally, multiple HPV types were found within one lesion (coinfection). In erythroplasia of Querat HPV type 8 was found in combination with other types of HPV [Wieland 2000]. In renal transplant recipients the number of keratotic lesions increases after several years. Also in these lesions a wide range of HPV types are recognized [De Jong-Tieben 2000]. In Epidermodysplasia Verruciformis HPV type 47 has been shown [Adachi 1996]. In Global nail dystrophy type 57 infection was found. [McCown 1999]
Although several different types have been described, recently minor variations in DNA composition have been within one type. Because of the genetic diversity of HPV the use of type-specific amplification is impractical for epidemiologic studies, for which accurate typing is essential.
Within the HPV region many gene sequences have been described both at the DNA and protein level such as E1, E2, E3, E4, E5, E6, E7, L1 and L2. Several methods use the one or more of the genes above such as PGMY LBA, SPF10 LiPA GP5+16+ combination Only one is using another E1 region than our invention does.
Several methods exist for the detection of HPV in general as well as for typing. Many use the polymerase chain reaction (PCR) for amplification of part of the HPV genome. For the PCR type specific primers can be used. As an alternative primers are used that allow amplification of more than one types. In some HPV tests primers are intended to amplify all types (general primers). These primers can be degenerated to a limited extent. With this approach one or more combinations of primers intend to cover for all HPV types (Jacobs, et al. J Clin Microbiol 1997 35:791-795; Bauer, et al., JAMA 1991 265:472477). After PCR sequencing can be performed for HPV typing. An alternative approach is to hybridise the DNA fragments to a filter containing different areas with different DNA fragments. Each area contains then DNA corresponding to one type. However, cross hybridisations may occur. In theory all different HPV types may be amplified and sequenced individually, but depending on the amount of types and variations to be known this will be an increasing amount of work.
Other approaches for the detection of HPV types are the use of restriction fragment length polymorphism analysis combined with an amplification technique, and another alternative for the detection of HPV is the use of an amplification technique in combination with single stranded conformational polymorphism (Mayrand, J Clin Microbiol 2000 38:3388-3393). Still other approaches are hybrid capture II and Ligase chain reaction (Yamazaki, et al., Int J Cancer 2001 94:222-227).
Yet approaches is to detect HPV is by in situ hybridisation (AmorTegui, et al., 1990 23:301-306; Unger, et al., J Histo chem. Cytochem 1998 46:535-540; Lizard, et al., J Virol. Methods 1998 72:15-25)) or in situ PCR (Jean-Shiunn Shyu J Surg Oncol 2001 78:101-109). On one histologic slide or cytologic specimen HPV type specific DNA fragments are necessary to obtain a signal. Thus, in theory recognition of any HPV types at least a similar number of slides/specimens is required to examine one kind of biologic sample. This would be a very laborious procedure.
Recent developments show after a PCR the use of a line probe or line blot assay to detect different types. Comparison of different line probes assays (PGMY LBA and SPF10 LiPA) reveals a difference in sensitivity for one assay: with PGMY LBA more HPV types 42, 56 and 59 and with SPF10 LiPA more HPV types 31 and 52 were detected [Van Doom 2002]. Also for the GP5+/6+ primers a reverse line blot assay has recently been described detecting 37 mucosal types [Van den Brule 2002 J Clin Microbiol 2002 40:779-787]. The concordance between different methods is moderate (Meyer et al. Dermatiology 2000 201:204-211; Vernon J Clin Mircobiol 2000 38:651-655).
Recently, ‘chip’ technology has been developed (see, e.g., U.S. Pat. No. 5,445,934). The term ‘microarray’ or ‘chip’ technology as used herein, is meant to indicate analysis of many small spots to facilitate large scale nucleic acid analysis enabling the simultaneous analysis of thousands of DNA sequences. This technique is seen as an improvement on existing methods, which are largely based on gelelectrophoresis. For a review, see Nature Gen. (1999) 21 Suppl. 1. Line blot assay and microarray methods both use circumscribed areas containing specific DNA fragments. As will be known in the art, line blotting is usually performed on membranes (Gravitt, et al., J Clin Microbiol 1998 36:3020-3027, whereas microarray is usually performed on a solid support and may also be performed on smaller scale.
The utility of DNA arrays for genetic analysis has been demonstrated in numerous applications including mutation detection, genotyping, physical mapping and gene-expression monitoring. The basic mechanism is hybridization between arrays of nucleotides and target nucleic acid.
Recently, the Point-EXACCT method was transferred to DNA microarray format, where a glass support is homogeneously streptavidin-coated. This coating is used to spot biotinylated probe to the glass slide and to hybridize a single-stranded target DNA to this nucleic acid probe. For detection a second probe is added, or the single stranded DNA is already labeled. The use of streptavidin-coated slides for microarray analysis is disclosed in WO 02/44713 the contents of which are incorporated herein by reference.
In conclusion, HPV types can be discerned with various laborious techniques. The present invention provides a further improvement of the microarray technique with coverage of any known HPV types on the array.